A driver of a vehicle is able directly to examine the region around his vehicle through the vehicle's windows, and indirectly through the vehicle's rear view mirrors. In this context, the driver is able to examine through the vehicle's windows predominantly the region in front of the vehicle and at the sides of the vehicle, whereas the region behind the vehicle may be examined using the vehicle's inside rearview mirror, and the regions laterally behind the vehicle may be examined using one or more of the vehicle's outer rearview mirrors.
Because of the restricted field of view of the driver and the geometrical relationships in a vehicle, that is, for example, because of posts between the vehicle's windows that hinder vision, it is generally not possible for the driver of the vehicle to examine all the regions around a vehicle without turning around or turning the head. Directly behind and in front of the vehicle there are regions that the driver is not able to examine. Similarly, there are regions at the side of the vehicle that the driver is not able to examine without a considerable change in the field of vision by turning his head. These difficult-to-examine regions at the sides of the vehicle are designated as blind spot regions of the vehicle, this region varying depending on the size and sitting position of the driver as well as with the kind and the setting of the outside mirrors.
European Published Patent Application No. 1 026 522 describes a system for monitoring a region at the side of a vehicle in a dynamic traffic environment. In this context, the system has an IR transmitting unit and an IR receiving unit which are situated at the side of the vehicle. These IR transmitting and receiving units define a lateral region that is to be monitored, an evaluating unit establishing whether an object is located in the monitoring region. The presence of an object in the monitored region is notified to the driver via a suitable display unit. A disadvantage is that object may be pointed out to the driver that are meaningless for the guidance of the vehicle.